Defective rate of flexible PCB design can be reduced by 90%

The number of circuits of one FPC can exceed 100, but it only occupies a thickness of 0.2mm. Although more expensive than flat cable, it is widely used in compact smart products. Especially mobile phones, smart bracelets and other scenes.

Today, let's talk about the golden finger design skills of welded FPC.

FPC

How about the quality of hardware PCB products? The design accounts for more than half

FPC welding can save two board to board connectors or one Zif plug connector, saving the cost of 1-2 yuan.

Therefore, welding FPC is selected for many middle and low-end commodities. (Handmade welding is faster than equipment mounting.)

If FPC is welded well, it is not only cheaper than connector, but also stronger than connector: welding is undoubtedly more solid than fastening.

The defect is that the relative connector in the welding area is larger and the maintenance is more complicated.

Although only one layer of gold finger matching welding layer can be made, the gold finger of FPC can not be made into only one layer.

FPC is a non-metallic material plate, with slow heat conduction. If there is only one layer of gold finger, the heat transfer of the electric soldering iron is not the same under the condition of manual welding, and it can not be welded.

Similarly, the tin hole punched on the PCB solder layer is also for heat conduction and allows the molten solder wire to flow between the upper and lower layers.

In the early days, PCB technical engineers only worked on double-sided pads. However, FPC is often short circuited in commodity production.

Later, it was found that the quality of FPC was not very good, but the ground stress was too high, which was very easy to crack. It must be improved according to the design method.

Finally, we invented the method of "wiring on both sides+additional vias", and finally solved this problem. No matter how you stack, FPC is not easy to break.

Cause of destruction: FPC is bendable, which is based on the fact that the overall copper mooring is pulled. After FPC welding, the welding surface cannot be stretched. Once pulled up, the supporting points are concentrated on the edge of the welding surface, and the edge will be broken.

After the two side wiring is changed, the problem of bottom edge breakage is not actually solved. However, since there are two layers of wiring, and one layer is broken, it is not easy to cause short circuit of data signal.